Pure-spin-current diode-like effect

Asymmetric charge transport at the contact of two materials with dissimilar electrical properties, such as metal/semiconductor and p-n junctions, is the fundamental feature behind modern diode and transistor technology. Motivated by this fact, we present a study of spin transport across the interface of two metals with very dissimilar spin-transport properties, Au and Pt. Spin transport is studied via spin pumping experiments in double magnetic layer Py/Au/Pt/Co structures. As the Py and Co layers have different ferromagnetic resonance fields, pure-spin-current can be generated by spin pumping from either Py or Co independently. The experiments reveal diode-like asymmetric pure-spin-current transport across the Au/Pt interface, where transmission from Au into Pt is more than twice as efficient as from Pt into Au. Our experimental results are well explained by extending conventional spin-pumping and spin-diffusion theory with boundary conditions for the spin chemical potential on either side of the Au/Pt interface.